1. Field of the Invention
This specification relates to a high voltage relay device, and more particularly, a high voltage relay device having arc electrodes in addition to primary electrodes.
2. Background of the Invention
Hybrid electric vehicles (HEVs) and fuel cell electric vehicles (FCEVs), which replace currently-used diesel or gasoline vehicles, are expected to be key issues in the development of vehicle engines, in the aspects of running out of oil riches and eco-friendly environment.
The HEV uses the existing engine and a battery as power sources. At an initial operation, the HEV is accelerated by using electric energy produced using battery power, and recharging/discharging of the battery is repeatedly performed using an engine and a brake according to a driving speed. The HEV exhibits higher fuel efficiency when a percentage of using the battery as a power source is higher. Accordingly, it is expected that a capacity of the battery is gradually increasing according to consumers' demands. In order to increase the capacity of the battery, the most convenient way is to increase a voltage. So, usage voltages of recently-produced batteries have increased from 12V, which is a conventionally used voltage level, to 200˜300 V, and in future, a further increase is expected. This requires for high insulating capabilities of peripheral electric devices. Accordingly, a high voltage relay which functions to power on/off a high voltage battery is newly developed now and high reliability of the high voltage relay is also required.
FIG. 1 is a longitudinal sectional view illustrating a high voltage relay for an electric vehicle according to the related art.
As illustrated in FIG. 1, a high voltage relay for an electric vehicle according to the related art includes a fixed electrode 1 having a fixed contact 11, a movable contact arm 20 having a movable contact 21 which is contactable with or separated from the fixed contact 11, an arc-extinguishing unit 3 for extinguishing arc A that is generated upon a contact or separation between the fixed electrode 1 and the movable contact arm 20, and a driving unit 4 for driving the movable contact arm 2.
The fixed electrode 1 is provided as a pair each having the fixed contact 11 on its end portion.
The movable contact arm 2 is formed in the shape of a flat plate, and provided with the movable contact 21 at a surface facing the fixed contacts 11.
The arc-extinguishing unit 3 includes a case 31 forming an arc-extinguishing space of the arc A using an insulating material, and a permanent magnet (not illustrated) for controlling the arc A generated between the fixed electrodes 1 and the movable contact arm 2. The case 31 is formed of an insulating material, for example, ceramic, and the pair of fixed electrodes 1 is coupled to an upper portion of the case 31. The movable contact arm 2 is installed within the case 31 in a manner of being simultaneously brought into contact with or spaced apart from the fixed contacts 11, and a downwardly-extending connection shaft 46 is coupled to a center of the movable contact arm 2.
The driving unit 4 includes a bobbin 41 in a cylindrical shape, an excitation coil 42 wound around a circumference of the bobbin 41, a yoke 43 disposed below the case 31, a fixed core 44 disposed within the bobbin 41, a movable core 45 brought into contact with or separated from the fixed core 44, a connection shaft 46 having one end connected to the movable contact arm 2 and another end connected to the movable core 45 through the fixed core 44, and a return spring 47 applying an elastic force to the movable core 45 to be separated from the fixed core 44.
The high voltage relay for the electric vehicle according to the related art will operate in the following manner.
That is, when power is applied to the excitation coil 42, the excitation coil 42 generates an electronic attractive force. The movable core 45 is then moved upward until being brought into contact with the fixed core 44, due to the electronic attractive force. The movable contact arm 2 connected to the movable core 45 by the connection shaft 46 is moved upward, in response to the upward movement of the movable core 45, such that the movable contact 21 of the movable contact arm 2 is brought into contact with the fixed contacts 11. Accordingly, a primary circuit which has been open may be closed.
On the other hand, when power supplied to the excitation coil 42 is cut off, the electronic attractive force is not generated from the excitation coil 42 any more. Accordingly, the return spring 47 which is interposed between the fixed core 44 and the movable core 45 returns to its original state. During this, the movable core 45 is pushed down. The movable contact arm 2 is also moved down along with the movable core 45, such that the movable contact 21 is separated from the fixed contacts 11. Consequently, the primary circuit is shorted or open.
In this instance, while the fixed contacts 11 and the movable contact 21 are brought into contact with or separated from each other, the arc A is always generated between the fixed contacts 11 and the movable contact 21. As such, both conduction and arc extinguishment are caused between the fixed contacts 11 and the movable contact 21, and thus the fixed contacts 11 and the movable contact 21 should be formed of a material which simultaneously satisfies electric conductivity and resistance to arc, in view of ensuring reliability. However, the two properties are difficult to be simultaneously satisfied due to a characteristic of a material, and a material satisfying them is very expensive and difficult to be processed.